CA 15.2 Extra exam qs
Q1.
(a)
1st box ticked
1
(b)
(permanent magnet) has no effect on the aluminium
1
iron is attracted (to the permanent magnet)
1
(only) the (permanent) magnet can be repelled (by the permanent magnet)
1
(c)
Level 3: Relevant points (reasons / causes) are identified, given in detail and
logically linked to give a clear account.
5−6
Level 2: Relevant points (reasons / causes) are identified, and there are attempts
at logically linking. The resulting account is not fully clear.
3−4
Level 1: Points are identified and stated simply, but their relevance is not clear
and there is no attempt at logical linking.
1−2
No relevant content
0
Indicative content
•
•
completing the circuit
turns the electromagnet on
•
•
•
there is a current in the coil
a magnetic field is produced around the coil
the iron core becomes magnetised
•
•
•
move electromagnet towards the blocks
the block is attracted to the electromagnet
moving the crane moves the block
•
•
switching off the current switches off the electromagnet
releasing the block
[10]
Q2.
(a)
correct plotting of all points
allow 1 mark for three or four correctly plotted points
allow ± ½ a square
2
line of best fit
1
(b)
as (number of) turns increases, number of paperclips increases
allow positive correlation
1
(c)
no paperclips would be picked up
1
(electro)magnet would not have been strong enough
or
magnetic field would not have been strong enough
1
(d)
take repeat readings (1)
to allow a mean to be calculated (1)
allow to identify / exclude anomalies
allow to reduce the effect of random errors
allow to assess the repeatability of the data
or
extend range of data (1)
to see if pattern continues (1)
allow to identify / exclude anomalies
or
use smaller intervals for number of turns (1)
to be able to see the pattern in the data more clearly (1)
allow to identify / exclude anomalies
or
use smaller paperclips (1)
to be able to detect smaller changes in strength of magnetic field
or so fewer turns required to pick up one paperclip (1)
or
increase strength of electromagnet (1)
allow increase current
so fewer turns required to pick up one paperclip (1)
Max 2 marks
(e)
the distance from the electromagnet
1
the size of the current through the wire
1
[10]
Q3.
(a)
The movement of liquid iron in the Earth’s outer core
1
(b)
will attract
1
will repel
1
(c)
Level 2 (3–4 marks):
A detailed explanation is provided that includes a coherent comparison of the
properties
of the types of magnet and presents a clear argument to support the use of
electromagnets. Logical links are made between relevant points and use in a scrapyard
Level 1 (1–2 marks):
Relevant points made about the properties of the magnets. An attempt at comparison
may be made, but logic is unclear and unstructured and links to use in scrapyard may
not be present
0 marks:
No relevant content.
Allow steel or iron for car body throughout
Indicative content
•
an electromagnet can be switched on and off
•
so it can be used to lift a car body
•
and release a car body
•
so it can easily be used to move car bodies from one place to another in
the scrapyard
•
a permanent magnet cannot be switched off to release a car body
•
so would not be as useful in the scrapyard
•
the strength of the magnetic field of an electromagnet can be varied
•
so an electromagnet can lift different masses
•
so can deal with different vehicles
•
but the strength of the magnetic field of a permanent magnet cannot be
varied or is fixed
•
so a permanent magnet can only lift up to a certain mass
4
[7]